Improvement in apparatus for dressing millstones



H'. ROBINSON ,av J. SMITH..

APPARATUS POR DRESSING MILLST'ONES.

No. 109,760. J9 f .Patented Nofv. 29, 1870.

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HENRY,v noBINsoN,A or LnwisHAnaND' JOHN sMrTH, or e'ansHA'L'roN, ENGLAND.

Leners raam; No. 109,760, aaa Novemberzg, 1870.

IMPROVEMENT in vaPrnrnA-rus Fonoasssme MILLsToNEs.

The Schedule referred to in these Letters Patent and making parl: of the name. 4

.and we do hereby declare the following to be a true and full description of the same, reference being had co-thc accompanying drawings. That is tosay,

Our improvements consist in dressing inillstones so that the cracks aremade coax-ser or'wider apart at or 'near the skirt or periphery of the stone tha-n near theA center thereof; and

In order to carry out our invention, we place in or near the eye or center of the stone a pivot, supported' by a flange, which may be screwedvor otherwise fast# ened to the said Istone during the operation of dressing. Upon the said pivot a hollow casting, having a curved slide aiixed thereto, is bolted or otherwise fastened, so that the said'castin g and its curved slide can revolve 'on the pivot by reason of the bolt-heads runningin grooves cut in the flan ge above mentioned,thc nuts on .the said bolts being screwed tight when the casting sothat it may work backward-and forward thereon by the rotation of the screw, and the nutk is causedto slide in its socket so that it may adapt itself to the varying distance between the said screwed shaft and the periphery of lthe slide-rest. 0r, instead of a screw, the shalt may be supplied with a-worrn-wheel gearing into a rack fixed tothe saddle of theslidc-rest, by which, or other equivalent means, the same result will be attained. t

.1 Upon the slide-rest is arranged a foot-step or bearing carrying a radial arm, on which works the toolholder, and the center from which thcradius of the arc of a circleforined lby the curved slide is struck n'iustbe at a greater distance from the circumference thereof than is the center of the millstone, so that, on rotating the screwed shaft, the slide-rest will be worked along the curved s lidc,.and the inner end of the radial arm carrying the cutting-tool will be moved a less distance than the outer end of the arm, thus causing the cracks to be coarser or wider apart at the skirt or peyriphery thanat the center ofthe stone.

The cutting-tool we prefer to use is the diamond,l

but any other hard substanceinay be employed.

fchine; and

, In order that our invention may. be clearly understood, we will proceed to describe the same vwith reference to the accompanying drawings, in which- Figure 1 represents a section ot' our improved ma-4 Figure 2, a plan of the saine.

Through the ilange a of the cone b screwed studs,

c, pass into nuts, d, let into the millstone d', by which said studs the machine is secured to the stone; but any other suitable means maybe used for thispurpose,

and studs, c, are also used for regulating the set orv tram ofthe machine.

Around the cone b, and fitting thereon at the points f, is the hollow casting g, having V or other slides, 7;-, projecting therefrom, the center i, from which the are of a circle formed by the said slides is `struck being at `a greater distance from the periphery'thereof than is the center ofthe millstoue, as seen in plan, fig. V2.

The upper part of the-cone b is screwed, and carries a nut k, which serves to tighten thecasting g on l the said conc while a crack is being made. This can be doncinstantancously by means of the bar I, or by any other suitable means. l

- Above the said cone, and resting thereiu,`is the vertical shaft m, carrying the bracket u for supporting the riggers o, around which passes the cord p for actuating the pulley g of the diamond cutter fr; and above this shaft is a second shaft, having its bearing in the ceiling or roof, and carrying the grooved pulley s, to which inotion'is imparted Vfrom a water-wheel or other motive-power, and which causes the driving-pulley t to rotate and give motion to the diamondcntter, as before explained. j Ong-the V-slides h is a sliding bracket or saddle, u, the arc of the slide whereof is struck from the same center as the are formed by the slides h, and this 1 to turn in its bearings g and tof'slide in its bearing h',

so as to adapt itself to the varying distance ofthe screw from the sliding bracket u, caused by the circular form ofthe slides It and the necessary rectilinear course of the screw.

The said screw c is supported in bealings i', and isv rotated by'the lever k actuating a pawl, l', taking into aratchet-wheel, m', the extent to which the radial arm a; is desired to travel along the slide,and,'therc fore, the distance apart of the cracks is regulated by the pin n fixed in a groove in the bracket o', against which pin the lever It strikes each time it is actuated.

The lever is here shown actuated by hand; but it may be worked automatically by the machine, -if de-V sired, and any other method -ot revolving the screw may be adopted, and, if desired, a worm, gearing into afrack' fixed to the sliding bracketu, may be employed instead of the screw.

lInstead of the radial arm a curved arm may bciixed to the said sliding .bracket, by which means the dress known as the circular or sickle-dress will be formed.

The operation .of the machine 'is as follows:

The radial arm a: is placed in position, either parallel with the lands of the ini-listone, or at an angle thereto. The lever or handle z is then actuated, by which 'means the tool-holder, carrying the diamond cutter c', is moved along the radial arm 9:,'thus forming a crack. The screw e is then rotated, causing the arm to be moved a short'distance along the curved slides h. By this. meansV cach crack or line will radiate, not from the center of the millstone, but from the point i, from which the are h is struck, or from some point adjacent thereto, thus causing the cracks or lines to bewiler apart or coarser at the periphery of the stone 'than near the center, as seen at 1i', andthereby preventing the disadvantage of the stone wearing away more rapidly near the skirt than near the center thereat that part. A

Having thus fully described the nature and particulars of our said invention,

XVe claima The flanged cone carrying the curved slide 71., having the arc of a circle, ,of which it consists, struck from a point at a greater distance from its periphery than is the center of the millstone, in conjunction with vthe curved sliding bracket or saddle n carrying the radial of, by reason of the greater speed at which it travels` arm x, by which means the cracks are made coarser4 

